Wet cell storage batteries having alternating positive and negative battery plates with interposed separators to prevent physical contact between the plates are notoriously well known. It is also well known from U.S. Pat. No. 4,026,000 to Anderson (the entire content of which is incorporated expressly hereinto by reference) that the individual battery plates may be enveloped in a folded sheet of porous film material. According to the Anderson patent, the overlapped edges of the sheet are continuously sealed to one another along their entire longitudinal extent. Other patent publications in the battery plate separator art which may be of interest include U.S. Pat. Nos. 4,407,063 to Johnson; 4,080,727 to Stolle et al and 4,085,560 to McClosky as well as UK Patent Specification No. 1,497,364 (the entire content of each publication being incorporated expressly hereinto by reference).